Reproduction process



United States Patent 2,957,411 REPRODUCTION PROCESS S. Black, Palo Alto, Calif., assiguor to The Howard Company, Palo Alto, Calif., a part- Howard Robert nership No Drawing. Filed July 9, 1958, Ser. No. 747,358 3 Claims. (Cl. 101-1495) This invention relates to a copying method and more particularly relates to a method of making spirit reproductions.

In the spirit reproduction process (sometimes known as the Direct process) a master is prepared which has a back surface having the material to be reproduced thereon as a reversed image in a soluble dye. The equipment now sold under the trade name Ditto is typical of the practice of the process. One common way of making such master copies is to provide a sheet with a dyed surface (commonly referred to as a carbon sheet) which is placed with the dyed surface in contact with the back of the master sheet so that when material is written or typed on the front of the sheet a dye image is left on the back of the master sheet. The dyes normally used are soluble in various organic solvents such as alcohol, acetone and the like so that when it is desired to make reproductions, a sheet of plain paper is lightly moistened with a solvent, such as alcohol, and is pressed into contact with the back of the master sheet, whereupon a small amount of the dye is transferred to the second sheet leaving the desired impression thereon. Since only a small amount of the dye is transferred on each contact, a relatively large number of copies can be made by this process.

Normally, such copies are made on machine and such processes work well when a large number of copies are to be made at one time. However, there are other instances when it is desirable to provide a method whereby only a single impression is made at any one time. For instance, in the keeping of medical records a patients name and a serial number may be placed on a master sheet and each time a transaction occurs the patients name can be transferred to the laboratory or other record thus obviating the possibility of errors. In such applications, it is obviously impractical to employ a machine and it is inconvenient to employ liquid alcohol, or other solvent. Thus, no practical method now exists whareby single reproductions by such process can be ma e.

It has now been found that satisfactory reproductions can be made employing a solvent which has been solidified. The solvent, incorporated into a solid material,

can be conveniently formed as a stick or pencil and when it is desired to make reproductions by this process it is only necessary to rub the stick lightly over the surface on which one wishes to make the copy and then place the master copy over the thus treated surface and press it in place with the fingers. This makes a complete- 1y satisfactory copy without the inconvenience and fuss of using either a mac 'ne or liquid solvent. The stick which is used employs a large proportion of solvent and a relatively minor portion of solidifying agent, and, since the solvent is volatile, all traces of the treatment of the paper disappear leaving only the dry desired image.

Various sticks may be employed for carrying out the method of the present invention. Such sticks may contain a solvent for the dye, such as alcohol, various petroleum solvents, ketone type solvents such as acetone and methyl isobutyl ketone or ester solvents such as ethyl acetate. However, it is generally preferred to use ordinary ethyl alcohol because of its ready availability, low cost and pleasant odor. Various solidifying agents can be used such as soap, higher alcohols, fatty acids and the like. One typical composition which has worked out well in practice is made as follows:

Solution A: Percent Stearic acid 5 Sorbitol 2 Alcohol 88 Solution B:

Sodium hydroxide 0.64 Water (about) 5 Heat each solution to C. Add solution A to solution B and agitate. Pour the mixture into molds and it solidifies as it cools.

The stick may be kept in a small case between useages and will last almost indefinitely until consumed. The stick may be partially wrapped in metal foil leaving only one end exposed thus preventing contact between the hands and the composition.

I claim:

1. A method of making reproductions by the spirit duplication process comprising rubbing a stick of solidified material containing a solvent for a dye over the surface of a sheet on which a reproduction is to be made and thereafter placing a master copy having said dye thereon in contact with said sheet.

2. The process of claim 1 wherein the stick contains References Cited in the tile of this patent UNITED STATES PATENTS Itasse Champion Oct. 4, 1898 

